Briggs 7hp Boils fuel, Hard Hot Restart, vapor lock [email protected]#~$

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  #1  
Old 05-04-06, 11:06 PM
fallguy
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Briggs 7hp Boils fuel, Hard Hot Restart, vapor lock [email protected]#~$

Have craftsman 7hp mower (briggs engine, 128602, 0246E1, intek OHV).

Starts like a champ when cold but hot restarts a major pain.

Have looked at kill switch wire, plug, plug gap, fuel types etc.

HERE IS THE NEW INFO. I put a see through inline fuel filter in and when this puppy has been given a good work out and you turn it off you can actually see the fuel bubbling in the inline filter.

Million dollar question what is making it do this ? ? ? Suspect this is causing a vapor lock type condition.

Have replaced fuel cap, same problem.

Does the carb have some sort of vent hole that could be plugged? ? ? ?

Is there something making the carb hot? ? ?


H E L P, anybody who whas seen this before, this is an incredibly pain in the @!$# to figure out.
 

Last edited by cheese; 05-04-06 at 11:32 PM.
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  #2  
Old 05-04-06, 11:34 PM
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I haven't run into this problem before, but if the engine temp is causing the problem, you might check the flywheel key for damage and the valve adjustments.
 
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Old 05-05-06, 11:37 AM
fallguy
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Is This a new clue ? ? ?

Cheese / Everyone,

I have been looking at the briggs parts diagram and guess what. The have added some additional gaskets where the carb attatches to the engine.

My guess is that found the fiber/plastic spacer was not doing the job to work naturally as a gasket.

Clue (1.) The original diagram shows only one gasket

Clue (2.) Mine came built with two gaskets (on engine side of spacer plate, sandwiched between the spacer plate, throttle assembly bracet, engine).

Clue (3.) Newest online version shows now the third gasket (I dont have) that goes on the other side of the spacer to now make a complete sandwich of all pieces with gaskets.

If I have a small leak (when hot) between the my spacer and carb (have no gasket there as now shown req'd). Could that be a source of my hard start problems ? ? ?

Could my fuel boil - vapor lock really be just air bubbles comming through a potential leak in this area that are allowing fuel to flood this puppy out when hot.

Thinking about adding this new third gasket, am I possibly on the correct track or crazy, thanks.

http://www.briggsandstratton.com/ipl...100/MS5116.pdf

gaskets 51, 51a, 51b
 
  #4  
Old 05-05-06, 11:49 AM
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I don't see any gaskets there that you should not have, so if you are missing one, I'd installl it. I'm not convinced this is the problem though, unless it causing the engine to run so lean it gets hotter than normal. Is there evidence of flooding with the engine hot?
 
  #5  
Old 05-05-06, 03:12 PM
fallguy
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Possibly Coil problem ?

Could this have nothing todo with the fuel bubbles (still weird though) and possibly be a coil problem.

The coil currently tests at approx 4900 ohms, have read on net that 2500 - 5000 is ok but maybe the coil developes a problem when hot.

What the best thing to do to check the coil in my situation, do a spark test when its hot.

(P.S. have checked the valves and adj ok).
 
  #6  
Old 05-05-06, 08:15 PM
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Have you checked the flywheel key?
 
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Old 05-06-06, 08:34 AM
fallguy
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Not yet, have never realy played with flywheel or flywheel key.

This could show up only when engine hot as a problem.

I will check this weekend.

Thanks.

If I have an intake leak wouldnt that make me run lean, cause motor to run bit hot (especially on hot days) and cause fuel bubbles, vapor lock.
 
  #8  
Old 05-07-06, 03:54 PM
fallguy
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Started tearing into to see if flywheel key had problem. Never mad it that far. Suspect I may hav found problem.

I have blown off the mower with air hose before but found spot I was not getting to. Found much oily packed grass inbetween cooling fins behind OHV box.

Will now wait for hot weather to see if that does the trick.
 
  #9  
Old 05-07-06, 11:04 PM
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I believe you've found the problem
 
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